Is there any way to add button on Lead info and company info page. Also can we call webhook from the trigger of the added button.
No, we don't have extensibility like this in place. You can only add custom fields to be displayed.
One hacky workaround you can use if you're desperate is adding a custom field of type "Boolean"
Then you can check/uncheck the box in the lead detail page, which will change that attribute value under the hood. You could setup a trigger campaign for Data Value Changes on that field...
You just gave me a flashback to doing this hack with Act! 2005 or something... wow.
Retrieving data ...