said by PhoenixDown:
They have traps (baited with food) where the mice will enter into a box and the box will shut behind them. You can then release them a few miles from home.
That's what I use in addition to ultrasonic experiments. Those are good options for people uncomfortable with killing/maiming.
My son likes to play with the mice caught in the box before releasing them in a nearby forest. He is convinced the exact same ones come back within a few days.