Lark’s Head or Cow Hitch knot for crazy cheap cable management with any string/yarn/etc. you have: https://www.thesprucecrafts.com/basic-macrame-knots-4176636
Or a noose knot can work too:
If the Cow Hitch knot loosens too much you can secure it with the Noose Knot (or a true Slip Knot).
Now I want to go prettify my cables with macrame…..