The title says it; cave sounds randomly play even though I am above ground.

I experienced this when playing on the seed "Trafalgar" (-1483818646) and chopping wood in the small forest near the spawn point. The Y coordinate of the forest is between 60 and 70, which may be low enough for cave sounds to play.

I also heard the sounds when roaming around the plains near spawn, with a slightly higher Y coordinate.

As cave sounds are random, I am unable to reliably reproduce the problem for a video, but it does happen relatively frequently (as MCPE-73361 says).