Cat and Mouse Game...

We have a cat (in our house). We have a mouse (in our garage). I've seen it a couple of times, and Hubs has seen it once. I also noticed it nibbled on the corner of a Christmas tree box that a friend gave me. (Which reminds me, I need to de-cardboard the garage). We put out a trap laced with peanut butter a couple of days ago. Said mouse has not yet discovered it.

Tonight, as Hubs studies for yet another test, we heard the little creature scratching in or around the wall. How does one get a mouse out of the wall? And, more importantly, how did s/he get there in the first place? I don't think there's a hole in our garage wall in that area.

Oh, and why aren't we letting the cat and mouse meet, you ask? For one thing, we have a scaredy cat, and we're not sure she's a mouser. Secondly, I don't want her coming down with some mouse-bourne illness. I would never forgive myself.