Camera view and mouse rotation

Hi, I have a little problem with my camera.
I have an old-school player control, like in doom 1-2 games, when character and camera rotation being controlled by mouse. So when I am close to the enemy, and click mouse button, I want
my character and camera to turn to the enemy, like they are looking at him. But when i am releasing a mouse button, my player and camera are both return to their previous positions.
So is there a way to match my mouse view with the current camera position. I know that I should add some value to my “controller yaw input”, but I don’t know how to calculate this value.

Problem solved.