Under what context are you asking?
This makes no sense if you're talking about a single number, but if the microseconds is an
interval, then there's a conversion available:
That said, generically, in universal
high school mathematics:
[Moved to the Lounge instead of General, as this is is not a display/graphics context]
Hz is a frequency. So likewise,
interval versus
frequency:
Hz = 1/interval
interval = 1/Hz
For example, frametime is an interval, and framerate is a frequency:
Framerate = 1/frametime
Frametime = 1/framerate
And mouse poll rate is a frequency, which also has a poll interval.
poll rate = 1/poll interval
poll interval = 1/pollrate
So 125 microsecond interval would be 8000 Hz frequency, in the context of an overclocked mouse poll rate.
1/8000 second = 0.000125 second = 0.125 millisecond = 125 microsecond