How to enable event cam "torpedo cam" in the campaign?
 

It seems no problem during historical missions ( you can deselect the no event cam setting )

I cant seem to get the event cam to work during the campaign.
Is there a mod to do this or how can i accomplish this without mods?

Welcome aboard!
 

Some mods automatically disable "event camera", which brings a small screen up to show how your torpedoes are doing or a sinking ship.
If you are using any mod like Wolves Of Steel (which disables the camera), you should check-uncheck the option in the options screen on the Main Menu.

I don't really know how other mods do, you should take a look at their FAQs.