A geofence related policy is defined with an Alert rule with "geofence event" type.  Details on entry/exit of one or more geofences and associated action (i.e. script)  have to be configured .  Finally, such rule has to be assigned to one or multiple device(s)/device-group(s) in the "Rule-Target" tab.

Also, each geofence can be re-used and referenced  in any number of alert rules desired.

The geofence(s) of any geofence rule will NOT be displayed on the map in the location tab of the targeted device.

Please also note that there can be BIG time delay for the alert rule to actually get triggered due to many reasons.  For example,  the device can be offline while it cross the geofence.  If the device get back online hours after crossing the geofence,  the alert will still get triggered on the server, but the timestamp is calculated based on some interpolation algorithm between the data pairs spanning very long time period and can be very inaccurate.  However, if the device has data-collection rule configured to record location data say at the shortest possible 2-minute interval, the timestamp calculated based on the interpolation will be much much more accurate than the case without using data-collection rule.  The above is based on my many days of field tests with real devices on previous MobiControl version more than 5 years ago, and I am not sure if there are any improvements or changes.in the more recent MobiControl release versions.