This plugin highlights non-ascii characters excluding whitelisted characters. It makes control characters, zero width spaces, full width colons and other dangerous characters that might break your code visible.
By default the European special characters are whitelisted. The whitelisted characters can be edited in the settings.
Sublime Text > Preferences > Package Settings > Highlight Dodgy Chars > Settings - User
The easiest way to install this plugin is with the Package Control plugin If you don't have Package Control installed, you can find instructions here: https://packagecontrol.io/installation
Once you've installed Package Control, restart Sublime and open the Command Palette (Command+Shift+p on OS X, Control+Shift+p on Linux/Windows). Type/select "Package Control: Install Package", wait while Package Control fetches the latest package list, then type/select Highlight Dodgy Chars when the list appears.