Basic electrical theory 101. You already confirmed that when you kill
the feed, the problem goes away. So now move to the next step.
Shut the power and at the junction box disconnect the wiring where the
feed is connected to your lights, so you isolate the problem.
Turn the power back on to see if you still get shocks.
If no, skip to step 2 at the bottom. Otherwise shut the power and
remove the feed from the junction box. It could be shorting on the
romex clamp. If you still get a shock, it's something underground.

Step 2: check your lighting circuits to see if anything is shorted.
Disconnect all the wiring and connect 1 light at a time to see where
the problem is coming from.