How do I make those cool looking spheres to demo PBR materials?



How do people go about making spheres such as the ones in this example to demo tillable PBR materials/textures?

I considered unwrapping a sphere and taking it into Zbrush, then applying a displacement map to add all the 3D detail on the surface of the sphere but I am wondering if this is the approach people use? I attempted to do it Marmoset using parallax mapping and whilst it looks good on the surface, the edges of the sphere are obviously not affected.

So I guess I have 2 questions.,

Whats the best approach to unwrapping a sphere so it will take a tileable texture?
What are the common techniques for creating the 3D topology on the surface of the sphere as seen in the link above?