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:

Noose Knot | How to tie a Noose Knot using Step-by-Step Animations | Animated Knots by Grog

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…..