I am also descended of Micahjah.
I don't know where he or Elizabeth are buried, but 2 of their sons are buried in Jordan's cemetery in Harrison county. This is an old cemetery, but it seems the first burials were associated with the start of the church and so Micajah and Elizabeth would have been dead some years before.

My guess is on their land or in a cemetery in the proximity of Mauchport - or between Mauchport and Corydon.