It has a medium high-pitched, short chirp or cheep, one-time, stops a bit then repeats, all times of the day or night then stops for lengthy periods. I thought chipmunk, but they are usually more repetitive vocally when they get going. I can't pinpoint where this is, I have a cat so it is probably hiding, suspect the heat ducts but not sure because the sound seems to alternate between the dining room and spare bedroom, kitchen or back hall, it is hard to track the sound. This has been going on for about a week now. I thought I might be hearing things, but my daughter was here and heard it and asked what it was.
I bought a havahart live trap for smallish creatures, had a dickens of a time getting it set, daughter figured out the final step, and loaded it with sunflower seeds and a peanut. Nothing has happened yet.