Surgical systems including a user console for controlling a surgical robotic tool are described. A witness sensor and a reference sensor can be mounted on the user console to measure an electromagnetic field distortion near a location, and to measure deformation of the location, respectively. Distortion in the electromagnetic field can be detected based on the measurements from the witness sensor and the reference sensor. An alert can be generated, or teleoperation of the surgical tool can be adjusted or paused, when a user interface device used to control the surgical tool is within a range of the distortion. The distortion can be from a known source, such as from actuation of a haptic motor of the user interface device, and the user console can adjust the actuation to reduce the likelihood that the distortion will disrupt surgical tool control. Other embodiments are described and claimed.