Mind probe
A mind probe was a device which obtained information from someone's mind and performed a neural scan to record brain functions. A mind probe could cause pain and even death.
In 2366, the Ferengi Farek wanted to study Lwaxana Troi to determine what neural configuration gave her telepathic powers, in the hopes that he could possibly duplicate those powers and gain profit from them. According to Tog, Farek's mind probes could kill Lwaxana. William T. Riker and Deanna Troi attempted to rescue Lwaxana while she was being tortured by the mind probe, and Lwaxana convinced the Ferengi to release Riker and Deanna to the USS Enterprise-D. (TNG: "Ménage à Troi")
Romulans were also known to use mind probes. (DS9: "Inter Arma Enim Silent Leges", "Extreme Measures")