Mobile technology is developing and impacting society at an accelerating pace. Since their release in 2007, over one billion smartphones have reshaped the daily lives of their users and their embedded technologies have become increasingly more powerful and miniaturized with each new model. Yet, the majority of the most popular uses of these devices do not take full advantage of their sensing, storage, computation, and communication (SSCC) capabilities. In this paper, we consider an experimental setup in which a smartphone is mounted to a ball and beam system using a 3D-printed mounting structure attached at each end of the beam. To perform feedback control of the ball and beam system, the smartphone's inertial and camera sensors are used to measure the angular orientation and velocity of the beam and translational position of the ball on the beam. To account for the nonlinear effects added to the system by the presence of the smartphone and its mounting structure, a feedback linearizing controller is used to stabilize the system. Simulation and experimental results are presented to show that smartphones and their various sensors can be integrated in the wireless sensing and control of physical systems as part of an emerging class of smartphone-mounted test-beds for research and education.