For which purpose do you need a NRUBS software after ZBrush?
As replied Spittle, ZBrush export only polygons and no NURBS datas, from quads to triangles, depending of your choices of optimization.
Software like Rhino can load the polygonal files, but you won’t have a lot of tools to work with, even if you can convert to NURBS (one poly=one patch), or use the TSplines on quad output meshes, but I think it won’t be possible on high polymeshes.
Please, tells us more about what you are looking for, your problematics, then, it will easier to give you a more accurate answer.
ZBrush is more and more used in the figure and toy creation, but perhaps not in all the toy filed 