The ovito installation from source code is required in case of using ovito python scripting in python.

Basically all steps are mentioned on the following Ovito page,

http://www.ovito.org/manual/development.build_linux.html

Known issues while building in Ubuntu system

1) Install libssh-dev, libqt5svg5-dev before using cmake as additional dependency

2) Change PYTHON_INCLUDE_DIR and PYTHON_LIBRARY accoerding to the version installed in user system

Adding ovito path in PYTHONPATH

After this set PYTHONPATH in the ~/.bashrc

Follow instructions in last section of

https://ovito.org/manual/python/introduction/running.html

You can check if PYTHONPATH is correctly set using

import sys; print(sys.path)