This plugin gives you the possibility to analyze the usage of your installed plugins.
You can find the plugin on sidepanel of Jenkins. Every user is able to use this plugin.
The plugin will give you a report on how much every plugin will be used in all of your jobs (see the screenshot below). Therefore it will analyze the used extension points of each job.
Plugins used in pipeline scripts would not be listed normally as used by jobs, because they are used dynamically in Jenkinsfiles.
An API is also available (https://github.com/jenkinsci/plugin-usage-plugin/pull/18).
Supported Extension points
This plugins will first iterate through jobs to gather those types of extension points:
and will add other plugins at the end.