Is it farther or further?
early 15c., "instrument for exploring wounds, etc.," also "an examination," from Medieval Latin proba "examination," in Late Latin "a test, proof," from Latin probare (see prove). Meaning "act of probing" is 1890, from the verb; figurative sense of "penetrating investigation" is from 1903. Meaning "small, unmanned exploratory craft" is attested from 1953.
1640s, originally figurative; "to search thoroughly, interrogate;" from probe (n.) and partly from Latin probare. Literal sense of "to examine with a probe" is from 1680s. Related: Probed; probing; probingly.
A slender flexible surgical instrument with a blunt bulbous tip, used to explore a wound or body cavity. v. probed, prob·ing, probes
To explore a wound or body cavity with a probe.