Excellon NC drill files from Altium
The CAM file is an Altium proprietary format, that will not be accepted by most PCB manufacturers.

What is commonly accepted is Gerber and NC drill files. IF you have got as far as having a CAM file, then it is likely that you also already have the NC drill file.
The NC drill file can be generated from the PCB design file, by going into File / Fabrication Outputs / NC Drill Files.
By default, Altium will open the NC file in Camtastic, where you can view the file you just created.

IF you only have a CAM file, then you can still the drill file, by going to File / Export / Save Drill ...