mazda mx6 buzzing in brake pedal

i have a 1994 mazda mx6. the other day i started the car. when i depressed the brake pedal to put the car in drive there was a buzzing noise coming from the brake pedal area. almost like an electronic buzzing noise. once i let off the brake pedal the noise stopped. my ex husband picked up the car to have it painted for me, and the problem has occured with him. what is causing this noise? does it have anything to do with the cruisee control being left turned on? i'm just guessing as i really don't have a clue. please help.
thanks.
peace,
theresa

  theresa