Twilio's Nomorobo Spam Score Add-on is used to detect robocalls by analyzing phone numbers through the Twilio Lookup API. To use this feature, developers need to create a Twilio account, install Python 3 and the twilio-python helper library, and add the Nomorobo add-on to their account. The `is_robocaller` function is used to check if a given phone number is likely a robocall based on its score from the Nomorobo Spam Score Add-on, which returns a score of 1 for confirmed robocalls. This tool can be used as a script to identify robocalls and can also be integrated into call centers or other applications that require phone number analysis.