get one's own back (on)
HAVE/GET/TAKE ONE'S REVENGE (ON), be revenged (on), hit back, get (back at), get even (with), settle accounts (with), repay, pay someone back, give someone their just deserts, retaliate (against/on), take reprisals (against), exact retribution (on), give someone a taste of their own medicine

[TahlilGaran] Dictionary of Contemporary English ▲

get own back
get (your) own back
to do something unpleasant to someone because they have done something unpleasant to you.
Fiona had deliberately stopped me getting that job and I was determined to get my own back.

She got her own back on her unfaithful husband by throwing a pot of red paint over his brand new car.
(often + on)

[TahlilGaran] English Idioms Dictionary ▲