Step::1 Login to your WordPress dashboard
Step::2 Go to the Plugins area of WordPress and click the “Add New” button
Step::3 Search for “Comment Attachment” from the text field on the right.
Step::4 Click “Install Now” then “Activate” buttons for the DCO Comment Attachment Plugin.
Step::5 Now go to Installed plugin and click on the Settings link under DCO Comment Attachment plugin
Step::6 Here you need to do some customization in the plugin like Attachment Image Size, Maximum upload file size, embed attachment, allowed file type, who can upload attachments.
Step::7 Once you are done with the customization, click over Save Changes button.
This is how you can allow users to add attachments in WordPress comments.
Visit our Blog for more details. You can also watch the video here.