Alex Cheparev shows how you can export Vector Displacement maps from both ZBrush and MudBox.

Displacement maps can help to add details to a model by using a grayscale map. It actually changes the surface of the model. There will be times where displacements alone cannot offer all the details needed.

The confusing process of exporting Vector Displacement Maps from Zbrush and Mudbox

An example would be that if you displaced an ear on the surface of an object, you would not get the underside to the shape of the ear lobe. Displacement maps can’t create an underside as it is always along the surface normal. It will always be perpendicular to the model’s surface.

Vector Displacement, however, sort of meld the best of displacement maps and normal maps together, but adding RGB color as a directional value assigned to the pixels in the map. This will allow you to displace much more detail in other directions rather than simply along the surface normal. With Vector Displacement, you can displace an underside to a shape.

Here, Alex Cheparev walks through creating vector displacement for a model, once in Zbrush and again using Mudbox. He continues to use the exported maps in Maya 2016 using the Arnold Rendering Engine.