Put a swag hook on my ceiling besides a light fixture

My current ceiling light fixture is off center. I want to put a swag hook on my ceiling to hang the light fixture electrical cable so it will be centered.
How to locate the stub on the ceiling?
I have a stub finder but I am not confident with it.
Will my existing ceiling light fixture help me to find the stub on the ceiling?

Greetings powah welcome to the Forum.

FYI, that's "Stud" Finder.

Finding a Stud to screw the hook into is a good idea, but, not all that necessary unless your fixture is very heavy.

The other choice is to buy a "Toggle Screw".
I usually get one that's got a screw about 3" long.
Unscrew the Wood Threaded screw out from the Hook.
Take the Screw of the Toggle, and screw it in from the back side of the Toggle, leaving the Ears of the Toggle facing the threaded end the screw.
Screw the Hook onto the Toggle Screw, make a hole where you want it, and stick it through.

Tighten it up and you're set.

Have a good Day !
S.W.