Bucket trap should do it.

Put peanut butter on the end of a yardstick. Put the yardstick on the edge of the counter or somewhere it goes, sticking out and just slightly balanced so that it stays on the counter with a little less than half sticking out. Put a tall kitchen trash can underneath it. The mouse walks out onto the yardstick, it tips down into the trash can, mouse + yardstick can be removed at leisure.

You can also rig up the yardstick to pivot and then return to the initial position: Tape a pen crossways to the yardstick using a little ring of backwards tape on the inside so it can pivot, then tape the pen to the edge of the counter via the two parts that are sticking out crossways. That way is a little more professional, and maybe removes some theoretical chance that the mouse can climb back up on the yardstick or get hurt by having it fall on him or her. You can also put some peanut butter in the trash can at the bottom, so the mouse can still have a snack while he or she is waiting.

The teeter-totter works.

But I gotta be real with you, mice do not do well with catch and release. Their survivability is low. For one thing, they now have to contend with whatever other critters fill their ecological niche in the release area. Second, if a mouse is sheltering in human homes, chances are that a properly wild area is going to have a very steep learning curve on food finding, predator avoidance, and shelter. Then, you have to actually find somewhere far enough from other humans that you aren’t just passing the buck to the next person (which is really shitty).

I couldn’t find the stuff I looked up back when we had a bunch of the little buggers swarm us, but survival rates of mice were something like 1/100 or worse, iirc. It was definitely a high enough range that I opted to go with as humane a death as feasible rather than have a high chance of it just making their remaining life miserable.

For real, if the things get dropped off within a mile or so of human habitation, it’s going to go back to what it knows. So you’d just be killing by proxy when the next person lays out kill traps or poison.

Hell, there’s also the disease factor. Moving an animal of any size into the habitat of others is going to risk spreading any diseases they might have. You save that one mouse, but kill ten others because whatever strain of bug it survived isn’t the same as the rest.

But the only realistic way to do it on a budget that I’ve run across is the teeter totter thing with a bucket/trash bin and bait on a stick. Not that no-kill traps are very expensive, and they are reusable. They also have the benefit of being able to catch multiples, which the bin method usually can’t reliably what with the chances of the stick coming loose.

We had a major surprise back then, btw. The trap we first used, I dropped while trying to transfer the mouse, a very pregnant female. She got away. Next bloody night, she was back in the thing with nesting material. Little thing seems to have decided that was a great place to give birth. We put her in an enclosure since the weather was icy and freezing. She had her young in that, and one survived (she ate the rest). Fuckers got a month in the enclosure being fed and sheltered lol.

Deer mice in specific are really territorial too, it turns out. So releasing them is essentially guaranteeing a fight since any area that is supporting one will be able to have a sizable population.

I fucking despise having to kill an animal that’s just trying to survive but crosses into human zones and can’t be allowed to stay. I just couldn’t find an alternative that wasn’t essentially having someone else handle the killing.

Live traps from Amazon are cheap. We have caught dozens and safely released them (far away from our house)