Abstract: An apparatus for detecting ultrasonic energy generated by a mechanical device and for applying lubricant to the device is presented. The apparatus includes a lubrication tool, such as a grease gun, which has a lubrication delivery element for delivering lubrication to the mechanical device. An ultrasonic transducer is contained in a housing which is removably attached to the outside of the lubrication delivery element such that the transducer makes acoustical contact with the lubrication tool. An electrical circuit, which may be attached to the lubrication device, produces an output signal which indicates the magnitude of detected ultrasonic energy. A method using such an ultrasonic energy detector in conjunction with a lubrication tool to detect the condition of a sealed mechanical rotating device and to determine when sufficient lubricant has been applied is also presented.