If they get in my house, all mercy goes out the window. They decided to nest inside my big powered subwoofer. I had horror thought of them chewing the wires. They would go into the box via the bass port. Put a trap a foot or two away from the port along the wall baseboard. Nabbed him within 24 hrs.
As previously mentioned, the chipmunks were coming in through the dryer vent, and chewed a hole through the dryer vent hose to access the house. Traps there too. Also put steel wool in behind the vent, post trapping, which seems to work well. Apparently, they won't chew on the steel wool.
Rats got into my garage. Ate a hole through the garage door jamb, then through the baseboard. Holes look exactly like what you see in cartoons. Set some big rat traps that you step on to set. Safe for my phalanges. Damn things have teeth too. Peanut butter worked best as a bait, btw.