Unity multiplayer: revert time on server to verify client

I'm building a multiplayer game like Fortnite in 2d for fun as a hobby project.

Right now I have the clients sending a command to the server then they want to shoot, but that makes it feel laggy on the client, as the shots are delayed a bit.

I would like to give the client authority over the shots and let them tell if they hit something. But I still wanna verify in the server that the client actually hit the target that the client stated. How would I do that? I know I could send the timestamp and check if it was correct, but how ?

 

https://developer.valvesoftware.com/wiki/Lag_compensation