Ground crewmember reported the nose wheel steering bypass pin was dropped on the ground and ingested by the #1 engine as the aircraft taxied. The aircraft returned to the gate for maintenance action.

Narrative

737-700 pushed back from gate to spot Bravo. Employee followed procedures to remove bypass pin when brakes were set per policy and procedure. Employee put the pin in left gloved hand then proceeded to disconnect the wireless connector that allows communications to the cockpit and the push back driver. Employee put this device in left gloved hand as well. Employee then walked from right side of nose to left side of nose and headed back to gate.Once back at gate was putting equipment back into the lead box and realized that something was missing. Employee retraced steps and saw the bypass pin on the tarmac to just about 3 ft. from the left of the nose gear. The aircraft had already powered engines and was in the process of turning to the right because there was an Airbus directly in front of him. Immediately notified the lead to get hold of supervisor or control center to have the aircraft stop or return to gate or something so that the bypass pin could be safely retrieved and removed from being a hazard on the tarmac/taxi area.The Captain/Crew did not get notified to stop and as the plane continued around the Airbus the bypass pin was ingested into the #1 engine. Employee and other members of the ground crew saw the bypass pin get lifted from the ground and into the engine and the noise that ensued. The flight had taxied away and when finally returned to gate; Maintenance met the aircraft.