Hi,
You will need to do it with JavaScript. You can then call into C# side with JavaScript extension. The code can be something like this:
Code: C#
webView.EvalScript(@"
document.body.addEventListener('click', function()
{{
eoapi.extInvoke('test');
}}, true);");
Here it runs a piece of JavaScript code to attach click event handler. Inside the click event handler it calls eoapi.extInvoke. This will call into .NET side and trigger the WebView's JSExtInvoke event. Obviously you would need to replace the arguments you pass to extInvoke with something that's more useful for you. See here for more details on how to use eoapi.extInvoke:
https://www.essentialobjects.com/doc/webbrowser/advanced/jsextPlease feel free to let us know if you have any more questions.
Thanks!