Can you put disc brakes on road forks originally intended for calipers?
To install disk brake, you need brake mount tabs on your fork/frame. Like this:


Original Image

And hub with mounts for brake rotor:


I've seen a few attempts to create an adaptor for fork/frame to install disk brakev tabs. But none were good enough for real life.

So your best route is to replace your fork and front wheel/hub.
But sometimes it is easier to get a whole new bike.