I am trying to import ddt module to my test but getting error

Python modules must be compatible with Jython 2.7 (written in Python language only, no native C-based parts).

See here for usage:
https://sikulix-2014.readthedocs.io/en/latest/scenarios.html#access-python-packages-from-sikulix-scripts-run-by-sikulix-gui-or-commandline

I'm looking at the code on github and it looks like they only used python to script
https://github.com/datadriventests/ddt and in doc it says it should work for Python 2.7

--- General remark:
If you want to do more complex things in SikuliX, then you have to fully understand Python/Jython.
When you want to use Python modules, that are not registered with SikuliX, then you have to find out your self, wether they run with SikuliX/Jython 2.7
You have to understand, how to make Python modules ready for SikuliX/Jython.

All this is not something that is supported here for every aspect of a special Python module.
The net might have more sources to help you in a special case.

In doubt you have to dive into the code of the module and understand structure, features and dependencies.

--- Your case ddt:
I had a look into it.
ddt depends on enum, which for 2.7 is only available as PyPi module.
If you succeed in making this available in the SikuliX context together with ddt.py, then it might work.

BE aware: all the setup stuff with Python might work in a Jython installation too (which is not the case with a simple sikulixide-jar usage). So you might install a module in a Python 2.7 context and then copy the relevant py files/folders into the SikuliX context or setup references to the Python stuff (see comment #1)