If the “Dims” checkbox is checked, then dimensions of the intersection points found from the first helper to the second one will be shown; instead of the usual site information.

If you happened to ALT-click on that checkbox; then it will toggle the display for these dimensions between metres and feet.

Note that you can also give dimensions in feet+inches instead of in meters when creating/editing objects. In fact, you can easily intermix between the two also during creation and/or editing activities.