Embodiments of the present disclosure relate to an apparatus, a system, and a method for detecting and indicating the operational position of a valve of wellsite equipment. The apparatus comprises a mount portion and a housing portion. The mount is operatively coupled to a non-moving part of the valve and the housing portion is configured to receive a sensor therewithin. The sensor is configured to detect the position of a moving part of the valve and to provide an output signal indicative of the position of the moving part of the valve. The position of the moving part of the valve is indicative of the operational position of the valve. The system comprises one or more such apparatus for detecting and indicating the operational position of one or more valves on a wellsite or well pad.