Let's hope its just a mouse. A couple of years ago we had what we thought was a mouse in our basement. Every night we would hear things falling in the basement. Thinking it might be a mouse I bought a mousetrap and baited it with peanut butter. Next day I go to check and the trap is gone. Search the basement and found it behind some stuff, licked clean. Figured we'll maybe its a rat. Get a rat trap and same thing happens. My wife says it has to be a squirrel and I say no way. When we first moved into the house I sealed any entrances and got rid of the mice. Just to make the wife happy I buy a medium sized have a heart trap and bait that with peanut butter. I get a text from my wife at work with a picture of a squirrel in the have a heart trap. Never could figure out how he got in, the only entrance would be the chimney that goes to the boiler. Took him out to the field behind my house and let him go. He never came back.