Microdisplacement has no effect at all I have tried several different configurations, with displacement, vector displacement, different color nodes, non-color, etc.: nothing seem to work. The bump doesn't appear.
Here is the final node config I have set up.
The UV setup is working, I am using it on the other nodes, for the albedo too, so the UV feed is correct.
Set the surface displacement to Displacement and Bump or to Dislplacement only (the default is bump, which will not deform the object, and only affect the shading, creating  &quot;fake&quot; relief.]1

Displacement needs vertices to operate on.
Here is a simple plane with 4 vertices and dislplacement. Here's the same plane subdivided 50 times: