This document describes a capacitive displacement sensor system used to measure deformation of up to 100 micrometers on brake discs under high stress conditions of up to 2000 RPM and 600 degrees Celsius. The key capabilities of the system are its high bandwidth up to 10 kHz, high accuracy with minimal temperature-related drift, and high resolution needed to detect the small deformations. The system uses non-contact capacitive sensors that generate a voltage proportional to distance between the sensor and surface. Electronics convert this to an analog output signal with good linearity across the 2 or 4 millimeter measurement range.