This never fails for me.
Nipper trap - the old-fashioned snap-shut-with-a-bang-would-take-your-finger-off type.
Peanut butter smeared around the post and the wood below the post, so mousey has to lick at it to get it off.
Trap set on a mouse run (which will always be along a wall or similar), or in a dark corner / corridor where the mouse goes - this is the bit you are most likely to be getting wrong if you are not catching any.
It might take a day or three before I get the first, but then I'll keep getting them until they're gone.