There are two features in Joomla that help you easily place modules directly inside articles:

• {loadposition} allows you to publish all the modules in a particular position.
• {loadmodule} allows you to publish just one particular module.

These are main steps you need to know to place a module to an article:

Step 1: Make Sure the Plugin "Content - Load Modules" is Enabled 

• Go to Extensions >> Plugin Manager
• Search for the plugin "Content - Load Modules"
• Check whether the plugin is enabled with green check

Step 2: Add module to an article

Assuming you already created a module and article. Next thing you need to do is add the module to the article. Remember that module must be published and assigned to a menu item where you need to show it.

- Use syntax: {loadmodule mymodule} if you like to load module by name

- Use syntax: {loadmodule myposition}if you like to load module by position

Conclusion

Besides the above methods you can add a single module with the assist of 3rd party extensions like Modules Anywhere. etc.