Surgical robotic systems, and methods of verifying functionality of a user interface device of such systems, are described. During a surgical procedure, the user interface device controls motion of a surgical tool. Proximity sensors of the user interface device generate proximity measures throughout the surgical procedure. The proximity measures are used to detect whether the user interface device is dropped and to responsively halt motion of the surgical tool. To verify an accuracy of the proximity sensors that provide the drop detection, a test is performed when the user interface device is placed in a dock. The test compares the generated proximity measures to expected proximity data. When the proximity measures match the expected proximity data, the system determines that the proximity sensors are functioning accurately and verifies that the user interface device is functioning safely. Other embodiments are described and claimed.