To a mouse an uncovered pipe is a sheltered escalator where cats can't reach them as they get from one free meal to another.
If you don't see a mouse it does not mean they aren't in the building: wall cavities, between floors, behind skirtings - the kingdom of mouse-kind.
Mice have no bladder so trickle urine wherever they are sitting, standing, dancing or eating.
They breed phenomenally.
Humane traps are not humane to people. Mice carry diseases that people can catch. A dead mouse will not trouble you again. A little nipper trap baited with peanut butter is swift and cheap.
Do not anthropomorphise or romanticise about them, they are vermin.