exploit (n.) Look up exploit at Dictionary.com
late 14c., "outcome of an action," from Old French esploit "a carrying out; achievement, result; gain, advantage" (12c., Modern French exploit), a very common word, used in senses of "action, deed, profit, achievement," from Latin explicitum "a thing settled, ended, or displayed," noun use of neuter of explicitus, past participle of explicare "unfold, unroll, disentangle" (see explicit).

Meaning "feat, achievement" is c.1400. Sense evolution is from "unfolding" to "bringing out" to "having advantage" to "achievement." Related: Exploits.
exploit (v.) Look up exploit at Dictionary.com
c.1400, espleiten, esploiten "to accomplish, achieve, fulfill," from Old French esploitier, espleiter "carry out, perform, accomplish," from esploit (see exploit (n.)). The sense of "use selfishly" first recorded 1838, from a sense development in French perhaps from use of the word with reference to mines, etc. (compare exploitation). Related: Exploited; exploiting.