My friend did compile itself version for Linux and have in Audio Position options microseconds, in official 2.3.2 release these are absent and in 2.3.3 alpha release is nothing mentioned about this feature.
There will be very few new features in Audacity 2.3.3 as this release will have a lot of “under the hood” refactoring.
I can log your interest in adding microseconds if you like.
May I ask why you would like this feature?
And a lot of bug-fixes too 
WC
I use audacity for analyse signal from sdr devices and milisecond interval is usually to big to measure it correct. When microseconds can be added in 2.3.3 will be great.
What sample rate do you record at?
Usually it is 192kHz.
So your signal is quantized to periods of just over 5.2 microseconds. Have you tried using a non-standard sample rate for the track, such as 200 kHz (5 μs intervals), or 1000 kHz (1 μs intervals)? If your system can handle that, then you could display the time in samples, and converting to decimal seconds would be trivially easy.
Thanks for clue, i will try it. My remark was based on differences between source code for linux(as far i understand my friend only compiled source code) and win release.