The mice I caught in my outbuilding...?

i'm an animale lover too. I would keep it as long as it's happy and doesn't try to jump out. I would not get a cage with wires mice that have been wild can squeeze out easily. I would leave him in the bin and add a water bottle that sticks to the side, a wheel, a food dish, and house. Don't forget to put a lid on the cage with air holes. Keep him safe, GOOD LUCK!