Yes. The "u" should really be the Greek letter "mu" - μ. If you can't see this correctly, the left line of the "u" should go further down. When you have technical difficulties writing it, a "u" is acceptable.
0.001 grams equals 1 milligrams (mg).And 0.001 milligrams in 1 microgram (mg), therefore 0.000001 grams (or 1 x 10-6) in 1 microgram.There are therefore 100,000 micrograms in a gram and in context...