I can’t stress this enough – do it right, so you don’t have to do it again.
The snap traps work. Using Fruit Loops or Cap’n Crunch as bait works. If you put the trap in the right place, you’ll find your intruder in it in the morning. Play games about it, and you’re only helping the mouse.
Get more than one trap just in case – you don’t want to reuse the same one (they’re very cheap, so just throw it out).