I want to know is there any way through which I can know my headphone percentage in taskbar or setting which can help me know these devices percentage and I can use it for my notification
You could try one of these gnome extensions.
First install extension-manager and then browse for the extension.
Select gnome shell version 46 if you are on Zorin 18 or shell version 43 if you are on Zorin 17.
how to install them in my system?
Here is a help site:
First install extension-manager in Software Store or via terminal
sudo apt install gnome-shell-extension-manager
Then open it and click on "browse". Search for
bluetooth battery meter
or
bluetooth battery indicator
and click on install to install them.
After the extension is installed go to tab "installed" and make sure that the extension is enabled.
You can test both (only enable one at the same time) and keep the one you like. You can also search for further ones.