Unaric Voice 

To add buttons and a related list, you have to change the page layouts for contacts, accounts and leads.

 

Step 1- Button: Add to Call Campaign

Add the button Add to Call Campaign to the Salesforce Mobile and Lightning Experience Actions

 

 

 

Step 2- Related List

Add the related list: Call Campaign Members

 

 

Step 3 - Search Layout

You need to edit the Search Layout for Salesforce Classic (also required for Lightning)

 

 

and add the button Add to Call Campaign in the Selected Buttons list.