I would just fold.

Even if we have the best hand, we're going to find it hard to get to showdown against someone showing strength.

When I get raised with a weak hand on dry boards, folding is almost always my default line, especially in limped pots where I have invested the minimum.

Bet/fold seem fine here. We're just gonna be crushed. They can limp AK, AQ, 66, anything really. I've frequently seen these microstakes fish have nutted hands playing this way. Also a raise on a dry board is generally stronger. Just watch how he plays and pick better spots. If we don't know what they're doing here then I'm very happy to fold and keep an eye on them because unless we have a note saying they play this way with bad pairs, or air, then making calls here isn't good.
If we figure he IS the worst player in the world and bluffs all the time for no reason then hey, maybe we'll take it all later when we have a better spot and more info.