If your headset does NOT have a large lock nut at the top with flats for a big wrench, I don't see how it could be cup-and-cone (loose ball bearings). The nut is needed for locking the cones in place after adjustment.

With the front wheel off the ground, turn the steering to either side and check for slow or notchy movement.

If you have the big nut right where the handle bar stem begins, place a large box lid under the bike to catch any loose balls that may fall out. If they don't hit the floor or become contaminated with dirt, balls in good condition may be reused if you are just doing a check.

Loosen the nut and push it up the stem and out of the way (maybe hold it up with tape). Lift the upper cup and inspect the balls. This will at least tell you the condition of the upper bearing. If there's enough grease and the bearing has been turning smoothly, maybe leave well enough alone for now. In any case, you've worked on this type of bearing and will know what to do.