Suggest getting a trail camera or borrowing one. It probably mice but the camera should tell you if it is sensitive enough. I haven't tried it on mice or small animals, just a thought. Here I got a regular outdoor IR camera and recorder I use.
But as you said it could be moles as I am covered up with them here. Tearing my lawn constantly. Oh why did I move to TN. When the yard is wet I sink up to top my shoes at times. Then of course I got darn armadillos, possums, and ground hogs (wood chucks) to deal with. It is like a war zone. I even had a rat to get into my house. I mean a rat. 3x the size of a mouse. Finally got him. Yet to find out how he got in.