An apparatus includes a body. The body includes first and second clamping mechanisms that are configured to grip a tubular member of a beam pump unit at first and second axially-offset locations along the tubular member, respectively. The body also includes a base positioned at least partially between the first and second clamping mechanisms. The apparatus also includes a strain gauge coupled to the base and configured to measure a strain on the tubular member as the tubular member moves. The apparatus also includes a gyroscope configured to measure an orientation, an angular velocity, or both of the beam pump unit as the beam pump unit operates. The apparatus also includes an accelerometer configured to measure an acceleration of the beam pump unit as the beam pump unit operates.