In order to use Batch with Unity, you will need to make a Unity plugin that calls the native code.
Here are Unity's documents on how to do so:
We also open-sourced our old, deprecated, Unity plugin.
While it is not fit for production, it provides a good example of how to implement Batch in your own plugin and can work as its foundation.
The source can be found here.
Please be aware that Batch offers no support for this plugin.