Change default weight unit to microgram

Looking for a plugin or simple code to change a product’s weight. Then we sell beads and the weight is low per piece, about 70 micrograms or 0.073 grams. Want to show micrograms instead of grams.

Have low or poor knowledge of code and am honestly a little afraid that it will be a hassle if I enter something in the code. Is there a friendly soul who can either explain how to do it, step by step or who can give tips on a plugin that does not cost too much.

//Per