Probe

To examine, as a wound, an ulcer, or some cavity of the body, with a probe.

Fig.: to search to the bottom; to scrutinize or examine thoroughly.

An instrument for examining the depth or other circumstances of a wound, ulcer, or cavity, or the direction of a sinus, of for exploring for bullets, for stones in the bladder, etc.

an inquiry into unfamiliar or questionable activities; "there was a congressional probe into the scandal"