To Add and Format Alternate Units

Click Home tabAnnotation panelDimension Style. Find
In the Dimension Style Manager, select the style that you want to change, and click Modify.
In the Modify Dimension Style dialog box, Alternate Units tab, select Display Alternate Units.
Under Alternate Units
- Select a unit format from the list.
- Select a precision value for the alternate units.
- Enter any prefix and suffix for the displayed dimension, including a space character if you want a gap between the dimension and the prefix or suffix.
Click OK.
Click Close to exit the Dimension Style Manager.