Mouseclick on network game?

Hello.
I’ve been using unity for a long time, but just recently started practicing network games. I wanna make a game where I can have many players at the same time, each controlling their own character. I want there to be cubes that I can click with the mouse, and the player clicking the cube would then be able to pick up (or just generally select that cube for himself). I have been using OnMouseDown function so far, but now that I have unknown amount of players in game, my old method doesn’t work. So far I’ve had a script attached to the cube and in that script I’ve had the OnMouseDown function. I have then dragged and dropped my player in that script in editor window, so i can then access it from the script. But how can I find out which player clicked the cube when I cannot drag them into the script before game starts?

Need more information:

What Networking solution are you using? E.G. - UNET, Photon, etc.
I only know Photon, but you can do that with [PunRPC] flag over a method, I believe UNET is [Command] I believe.
Then you gotta make it be like hey, player3 clicked the cube, give him/her the permission to move it.

But [PunRPC] / [Command] I believe is what you’re after. or in other words “Remote Procedural Call”