Humm, maybe with this: So how does microdisplacement work now in 2.79?
One should put a multires modifier to the low poly mesh, do some subdivisions, shrinkwrap to the high poly mesh and apply the shrinkwrap. Then it should be possible to bake a displacement map using the method above. Maybe a height map can also be extracted using only the z values?
I’ll do some experimentation when I have the time.