Ultrafast lasers have proven to be an effective tool to improve the process quality when machining hard ceramic materials such as silicon carbide, silicon nitride and alumina, as well as hardened metal alloys including titanium. We have developed a novel in-line optical depth measurement system that is coaxial with the laser processing beam and measures the part surface location in real-time (80 kHz) and has a depth range of 2 mm and a measurement repeatability of ±3 µm. We integrated a 40W ultrafast IR laser (1030 nm, 400 μJ, 190 fs) into a 5-axis motion system and a custom scanhead that creates a common optical path for the process and sensing beams. The sensor can be used to monitor the part surface location in real-time for controlling process parameters such as focal plane adjustment and laser power, or used in a 2-D scanning mode for layer-by-layer process monitoring. Furthermore, the scanning system can stich multiple fields together in situ to create a full 3-D point cloud of the part for inspection and metrology. The system was tested on ceramic (SiC, SiN, Alumina) and titanium alloy (Ti-6Al-4V) samples. Using the beamline optics in our custom scanhead, we achieved material removal rates on the order of 0.2 mm³/s for ceramics by using the feedback sensor to control the beam delivery payload and maintain optimal laser focus. Post-processing, the part was scanned with the sensor to create a point-could map and dimensional tolerances were assessed.