I have a mouse, and it's not a pet

Hopefully it's only one, haven't seen only one at a time so I guess it's all the same one. I've set several traps, so far it doesn't help. Several different types, some with poison which it doesn't eat it. And some trappers, with peanut butter as bate. It has ate the peanut butter but the snapper don't snap.
I live on the third floor of a four story apartment complex. How the hell can I get a mouse!! And how the hell can I get rid of it!! It makes me very paranoianical.