Just a note:

Displacement, like bump mapping, only goes in one direction. For a good close-up, you'll need more than that. The best option would be to use custom hi-res geometry props in place of a the nipple group in such a figure (IF a figure is what you're talking about) combined, perhaps, with a good normal map to take care of what wasn't modeled. With the high-res geometry, you can create details on all axes. Also, severe displacement does not play well most of the time with certain sorts of materials and lighting setups. So, trying to use it, alone, to create a nipple, if that's what you're trying to do, isn't going to look very good. But, for certain effects, like pores, that are normally "inferred" instead of actually being "seen", displacement should do a decent job and you could even combine it with bump mapping, if you wished, as long as you planned both well enough.