If the brakes are truly dragging, this will quickly overheat the rotor and caliper and can cook the bearings, etc. and cause all sorts of expensive damage- so if this is the case, quit driving it!
But what you could be hearing is the brake pad's wear indicator that hits the rotor and causes a hell of a noise. The wear indicators are made to make you see what is going on.
It can be temporarily bent back away from the rotor- but the pads need changing and the rotors checked/turned/replaced ASAP if this is the case.