Format symbol label text

[Zeke]

In ArcGIS Pro, is it possible to format the legend label text? I found this instruction - 'Format numbers in legend labels', but 1) I'm not trying to format numbers, and 2) under Advanced symbol options the only option available is Feature level masking

What I'm trying to do is format mg/m3 to µg/m³, as in 0.002 µg/m³ for the legend label. Thanks.

edit: I was able to get all except the superscript by copy -> paste. Anyway to do that?

edit 2: I ended up putting 3 in as its own text and superscripting that. Not elegant, but works.

[RobertBorchert]

Now the following is crude but it shows it does work as a label and in the legend