One way is to use non-waxed dental tape (flat) or regular floss.
1. Starting with the line, thru the strands of string, wind back and forth over the spot 1/8 to 1/4".
2. Before you reach the height and final shape, take a second piece of floss about 6" long and doubled over the winding with the loop to the right if your right handed. Pinch with fingers of the LH. while winding as follows.
3. wind tightly over the loop toward the closed end, 5-7 turns, cut the winding thread about 3" from the winding and insert the end through the loop.
4. pull the two ends tight and pull the end of the winding thread under the over-wrap.
If you wind the floss/tape to tight over the loop, it will be hard to pull it through, without breaking the loop. Go easy at first.
Winding the nock in a X pattern is sometimes easier than trying to keep it all straight. Keep it tight. Almost to the breaking point, when winding the initial wraps.
Seal with a drop of super glue, or fly tyer head cement.
Alternate wrapping can be done with knots used in fly tying, wip finish or typing 2 hooks on a leader. Some are more involved then the above. The simplest is several half hitches.