Unfortunately, if you don't have high-precision scales, there is no way to measure such small quantities as 60 ug.

You didn't explain clearly what is the final concentration you need, because "I need 60ug of powder" sounds weird, usually people write, "the final concentration was 1ug/ul" or something like that. If you clarify this point I can help you with dilutions.

But if you just wanna know how to get 60ug of the chemical from 1mg/ml stock solution, it will be taking 60 microliters out of this 1mg/ml solution.

Because if you have 1mg/ml solution, it means you have 1000 ug of your chemical in 1000 ul of your diluent. In other words, each ul of this solution contains 1 ug of your chemical, and to get 60ug, you need to take 60 ul of it.

But I am not sure that's what you need. Be careful and don't make a mistake, read the exact phrase in your source, how much of what in what you need.

Prepare your stock solution (1mg/mL = 1000ug/1000uL) by diluting 1mg of your powder material in 1mL phosphate buffer saline.

Then take 6OuL of the stock (it contains 60 ug of your powder material in the desired buffer) to carry out your experiment

Thanks a lot Yulia Panina and F. Romain Fouelefack for your help.