1) Espionage. This is the primary use for Scanning and Probing. Scanning and Probing, as defined before (IA) are both methods of getting information from a target, potentially an enemy, without their immediate consent. 2) Assessing an Individuals Energetic Information. Another primary use of Scanning, not as much so Probing, is determining energetic information of another individual, be it friend or foe. 3) Mind Reading. This is the general concept understood when one says Mind Reading, specifically, this is how a person gains unchecked access to information from an individual, whether the person is presently thinking it or not.
Of course, the first step here is acquiring the target. For this particular exercise, you should begin by extending a tendril from the edge of your mind or shields. This process is difficult to describe, but can be done using the "visulaization" method amongst those who have programmed their subconscious properly, to manipulate Psi and perform acts based on biofeedback.
Reach the tendril towards the target, gently, because a forceful scan/probe can be extremely painful,and less than covert. For a cursory scan of surface thoughts, simply brush the tendril against the edge of the targets mind, or energy field. For a probe, push the tendril into the mind, rooting around and navigating to find what you want.