I'd you mean a parallel port to USB adaptor designed for printers etc then the answer is no. (If you mean a CNC hardware step generator that plugs into USB and has a parallel port like Smoothstepper that is different).

CNC requires real time control.

That either means:
1. operating system generating steps in real time and putting them out the parallel port. A USB-parallel adaptor is actually emulating a parallel port. It has a chip to convert serial (USB) to parallel. It will not pass real time signals

2. An external CNC motion controller card / hardware step generator (e.g. smoothstepper, mesa cards, many others). These may use USB, ethernet, PCI or parallel port. The precise timing of step generation is handled by the external card.
Again a USB-ppt adaptor / emulator will not work


Option 1. Is becoming less common due to cheaper better external step generators and parallel ports are disappearing.


(Only something specifically designed for CNC will work)