With the Unsend feature, they'd be able to delete it from both their own and the recipient's conversation, the MailOnline reported.
The tool can be accessed in the Messenger app by clicking on the 'Edit' option.
The screenshots show users would have a certain amount of time to unsend a message after they've sent it.
Once a user selects the feature, a pop-up window will appear asking them to confirm their choice.
The notice adds: "Your message will be removed from the chat, and you."
It's unclear when or if this feature will appear for users.
"Facebook internally tests products and features before they ship to the public so we can ensure the quality of the experience," a Facebook spokesperson told TechCrunch.
Facebook wouldn't be the first tech platform to test an unsend feature.
Earlier this year, Instagram began allowing users to unsend messages sent via Instagram Direct.
To do so, users press down on a message and wait until a window pops up giving them the option to 'Copy, Paste or Unsend.'
They hit Unsend and it will remove the message from the chat. However, the recipient may still receive a notification on their smartphone saying you sent a message, as well as its contents, depending on their settings.
Gmail also has an 'Undo Send' feature which lets users unsend messages within a 30 second window.
Facebook began feeling the pressure to release an Unsend feature after its CEO got caught deleting messages.
Three sources claimed old Facebook messages from Zuckerberg had disappeared from their inbox.
The recipients were not notified - raising concerns about what the Facebook CEO could be hiding.
Facebook claims the change was made after the 2014 Sony Pictures hack, when a mass data breach at the movie studio resulted in embarrassing email histories being leaked.
However, the lack of disclosure angered some users, along with the absence of a similar tool to recall messages for normal users.
The fact the company is prepared to make exceptions makes a mockery of its statement that it wants to 'make the world more open and transparent', experts said at the time.
FACEBOOK SAYS IT SCANS ALL OF YOUR MESSENGER TEXTS
Facebook scans the contents of messages that people send each other on its Messenger app blocking any that contravene its guidelines.
The scandal-hit firm, still reeling from revelations surrounding Cambridge Analytica, checks images and texts to ensure they are in line with its community standards.
CEO Mark Zuckerberg confirmed the policy during a podcast interview with Vox's editor at large, Ezra Klein.
Messenger says that it doesn't use data from messages it has scanned for the purposes of advertising, according to reports in Bloomberg.
The company told the website that it uses the same tools to prevent abuse in messages that are in place across Facebook as a whole.
Users are able to flag posts or messages that they feel are in violation of the site's house rules.
This will either cause one of the social network's community operations team to manually review the content, or automated systems can also make decisions.
"For example, on Messenger, when you send a photo, our automated systems scan it using photo matching technology to detect known child exploitation imagery or when you send a link, we scan it for malware or viruses," a Facebook Messenger spokeswoman said in a statement.
"Facebook designed these automated tools so we can rapidly stop abusive behaviour on our platform."
