A TDC chip would only get you down to around 20ps resolution so I suspect you need a custom device or custom circuitry. The TDC principles can possibly be used but you need even higher resolution. I have used Guide Technology boards in the past - they get down to 8ps. although the continuous ones get down to 2ps with averaging. This is fairly serious design to do that from scratch.
A TDC chip would only get you down to around 20ps resolution so I suspect you need a custom device or custom circuitry. The TDC principles can possibly be used but you need even higher resolution. I have used Guide Technology boards in the past - they get down to 8ps. although the continuous ones get down to 2ps with averaging. This is fairly serious design to do that from scratch.
Search IEEE papers for TDCs (Time to Digital Converters) - it should give you some ideas about the techniques to use. Also, it is worthwhile searching for theses at the University of Oulu. They have done a lot of research for Noptel on laser rangefinders and as they were PhD or MSc theses the information is freely available. https://www.oulu.fi/english/