Robson had denied being molested by the late singer in Jackson's infamous 2005 child molestation trial but in a recent about turn, the choreographer filed a lawsuit against Jackson's estate, alleging Jackson sexually abused him for 7 years as a child in 1990.
Robson, 30, has filed an amended complaint where he claims that the alarm would go off whenever someone came within 30 feet of Jackson's room.
Robson claims Jackson also hung a "Do Not Disturb" sign on his bedroom door, TMZ reported.
The choreographer claims he testified in favour of Jackson in 2005 because the singer had brainwashed him.
Jackson's estate has rubbished Robson's claims as "outrageous" and an attempt to get money out of late singer's estate.