I have no idea how to hack someone's Grindr. The words 'with care', 'clandestinely' and 'furtively' come to mind. However, other more important words also come to mind. Here they are:
Ask yourself WHY you'd want to do this
Having racked my brain, I can think of just two, rather pitiful reasons for hacking someone's Grindr accounts - cruelty or jealousy. Both are pretty lame and both are bad for your soul. In fact...
Jealousy rots people from the inside out
It's very destructive. It makes you believe that other people are always having more fun/ getting more chances / living more fully. They're not. Just focus on yourself and screw what anyone else has or does.
Accept that you are not in control of anyone else...
...or their Grindr account. Realising that you are not in charge of anyone's actions but your own is a very liberating experience. It lets you stop worrying about how other people behave and simply make sure your own behaviour makes you happy and proud.