The knob part attaches to the base with magnets so you can use it as a normal knob for drawers, light doors etc. The base part has a hole to sink an m4 screw. 

Once you remove the magnetic knob-part it is quite impossible to get a grip on the base part. This way your belongings should be (at least a little bit more) secure. Works great for kids too. The knob has a little hole through it so you can attach a string or similar and hang it somewhere out of reach. 

Apply a color change at a height of 1.8 mm to embed the magnets into the base.

Feel free remix for other magnets, screw sizes etc. 

This specific one is designed for magnets with the size of: 

5 x 1 mm - 5 x 1.5 mm

for example these ones: https://www.amazon.de/HHOOMY-Neodym-Magnete-Aufbewahrungs-Permanentmagnet/dp/B07T13H3R5/ref=sr_1_19?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=2TX4SBQLT2HNO&keywords=magnet+5x2mm&qid=1667681277&s=kitchen&sprefix=magnet+5x2mm%2Ckitchen%2C68&sr=1-19