Yes you can use WD40, and you would lube the pivot point of the upper side of the pedal.
You*ll have to climb in there so you can reach under the dash to see where to spray for the brake pedal components.
As long as it's just a noise inside the vehicle being made by pushing the pedal, you should be able to spray it with WD40.
If the noise doesn't go away, or that was not the problem, then you will need to have it looked at to make sure there isn't a problem with the braking system.
〉 Answered on Apr 21st, 2008 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines