Hello,
We bought our house recently, and it was built in the 1960s. Well, the wiring too is old and has not updated since then. The original fuse, two-wire system, and metal boxes are still in place throughout the house. To reduce electrical faults, I had hired an electrician to do some electrical changes to the wiring. So the electrician suggested to add a ground wire to the back of the metal box that would ground the outlet, and later it could be replaced with a three-prong receptacle. Next, if a GFCI is installed at the starting of a series of outlets, the following receptacles would trip the GFCI if faults happen. Is this a useful grounding method for two-prong outlets? What are your thoughts on this?
Thanks!

Your electrician is right. If there is a ground present, connecting it to the receptacle is really all you need to do but the GFCI solves the problem if that ground is compromised or non existent. It was common to use the old style Romex with the 16ga ground in the late 50s, early 60s, connected to the boxes but still installing the 2 pin receptacle. There was a thread here about that with the dates that showed up in the code. Just bear in mind most places do not adopt the new code right away.

This is were we discussed the small ground conductor
https://www.electrical-contractor.n...ed-grounding-wire-in-nmc.html#Post220515

Thank you!