@m_adam thanks for your prompt response. I'm looking forward to hearing from you.

I would like to implement an add-on that should launch a background thread when ZBrush starts, and can export current scene to a common 3D model format to a specified path. This exporting function will run in the background thread and be triggered by an external program, not ZBrush.
I looked into GoZ and ZScript, it seems they do not meet my requirements.
Does anyone have any ideas?