The Pick-Lock Wristwatch is a mechanism designed to crack the combination of any safe, and concealed as a small wristwach.
Peggy Carter learned from the fence Spider Raymond that he had the formula for Nitramene but not on his person. He kissed Carter, but was rendered unconscious by the Sweet Dreams Lipstick she was wearing.
This gave Carter time to use the Pick-Lock Wristwatch to open the safe in his office. She was surprised to find that the formula had been weaponized; instead of finding a document, Carter found an active bomb.