Here is a summary of the steps presented in this guide:

\C0202021.\C484848 Import the object (press Tool>Import).

\C0202022.\C484848 Store the cage (press Tool>Morph Target>Store MT).

\C0202023.\C484848 Activate Edit Mode (draw in canvas, press Transform>Edit, hotkey '\C020202T\C484848').

\C0202024.\C484848 Subdivide the object (press Tool>Geometry>Divide, hotkey '\C020202CTRL+D\C484848').

\C0202025.\C484848 Sculpt the object using any of ZBrush's powerful features.

\C0202026.\C484848 Switch to level 1 (adjust Tool>Geometry>SDiv).

\C0202027.\C484848 Recall the cage (press Tool>Morph Target>Switch).

\C0202028.\C484848 Generate the map (press Tool>Displacement>Create DispMap).

\C0202029.\C484848 Export map (press Alpha>Export) and tool if desired (Tool>Export/Save As).