A Probe can be a noun or a verb. As a noun, a Probe is a device or mechanism to reach places or things not accessible otherwise. Examples of Probes are medical probes to assist doctors in seeing your internal organs, as well as devices to perform the operations. Often they can use the two simutaneously. NASA uses probes to go to the Moon, or to Mars.
As a verb, to Probe is the act of exploring or investigating places or things not accessible otherwise. Computer Hackers (Both legal and otherwise) probe vulnerabilities in computers or computer networks. Doctors probe your internal organs. Law Enforcement Agents probe into unsolved cases. Psychologists probe into your conscious as well as subconscious thinking.