Be very careful when working with that older wiring. I encountered similar wiring in my 1920’s era home and removed all of it because it is a potential fire hazard if disturbed. The insulated coating cracks and frays easily. There also is no ground wire unless the box and conduit are grounded and you attach a ground to the box.
The good news in this is that these individual conductors run through conduit, so it is very easy to run replacement wires as well as add the necessary neutral wire. Because of the conduit, there are no staples restraining the wires inside of the wall, so you can use the old wires to pull new wiring or pass a fish tape through the conduit after removing all of the old wiring between the fixture and the switch box.
Replacing the wires adds to the cost, but added safety and peace of mind is well worth it.