There is a video tutorial here that may be useful:
This should produce a displacement map that you can then use to be imported into other projects.
...this displacement feature is currently only supported in cycles unfortunately :(
With the node selected in Blender, press the tab key. This will open up the node group for inspection and editing.
Under the Material Properties tab, go to Settings -> Surface. Once there, you will see a drop-down box called Displacement. Change this to Displacement Only or Displacement and Bump and you should start seeing displacement in the viewport.
You will need to set the 3D viewport shading to Rendered mode to see the effect. You can do this by clicking the buttons in the top right of the viewport or, with the mouse in the viewport, press the Z key and select Rendered in the menu that appears..