Adds a measurement showing the minimum and maximum deviation between two surfaces. This tool creates a locator showing the deviation between the two objects, labeling the minimum, maximum, and mean.
It also displays a deviation comb indicating the deviation across the length of the objects.
Objects in reference layers can be selected from within this tool.
Access this tool from the Locators palette:

Surface to Surface Deviation Options
Check/uncheck the boxes to turn the different labels and comb on or off.
The labels can also be toggled on/off from the Information Window.

When Show Comb is on, you can right-click a comb sample in the viewport to display the deviation value at that point (see Display deviation values in the viewport.