More than 5 billion people have access to mobile phones globally. These devices, many of which are smartphones with multiple integrated sensors (e.g., global positioning system receiver, camera, etc.), provide a myriad of opportunities to support scientific investigation by researchers and citizens alike. Many smartphones even contain geophysical sensor technology that can be deployed for geophysical data acquisition. However, there is limited research on the ability of these sensors to acquire scientifically useful geophysical data. In this study, we evaluate the efficacy of a magnetic field sensor in a smartphone to address this knowledge gap. Using a free application called AndroSensor, a preliminary experiment was conducted to map buried pipes at a test site and to test the efficacy of the AK09911C magnetic field sensor inside a Samsung Galaxy Note 4 (Android OS) smartphone. In addition, data were acquired over the test site using the commercially available Geometrics G858 Cesium vapor magnetometer for comparison. Results showed that the smartphone was able to identify all three buried pipes and compared favorably with the Geometrics G858. For the primary experiment, a walking survey was conducted over a landfill in order to compare the smartphone with the G858 Cesium vapor magnetometer. Results showed little variation between the G858 Cesium vapor magnetometer and smartphone magnetic field sensors when within the boundaries of the landfill. This proof-of-concept study suggests that smartphones with geophysical sensors potentially provide a more affordable approach to the acquisition of geophysical data, especially at academic institutions with limited access to expensive commercially available geophysical instrumentation.