Playing against a Zombra can be super annoying. What is her utility though? Not sure how to play her.
It depends on the comp.
If you're running two healers, keep one main, convenient health pack hacked and do a loop of placing Translocator on it, flanking the enemy and whittling them down while going back to the health pack once you take a bit of damage to build ult. Focus hacks on critical ability-centric heroes (Genji, D.VA, Rein, etc.) and communicate with your team to focus fire them. Use EMP during team fights, or on characters with mainly shield health (Zen, Symmetra, Zarya) to eliminate them quick.
If running one, use your hacks on as many close-by health packs as possible and maintain them so your team can farm ult and play aggressively. Continue the loop of Translocate--->Flank--->Heal. If you work with your team to constantly heal chip damage you take, you'll be getting EMP every team fight or every other team fight.
Make sure to hack extremely important enemies when they are ulting. Genji during Dragonblade, Winston during Primal Rage, Baby D.Va while she ults/is building meter, McCree during High Noon if you can swing it, Mercy when flying in to res, etc. Also, if you have EMP during a team fight and you're winning and a Symmetra has her TP up, don't be afraid to EMP the Teleporter/Shield Gen. Kills it near instantly after an EMP and a few shots. Can swing a game in your favor.
Sorry if this is a little obvious lol