I believe that what OP was actually asking about is called Caret Notation.
Caret notation is a notation for unprintable control characters in ASCII encoding. The notation consists of a caret (^) followed by a capital letter; this digraph stands for the ASCII code that has the numerical value equivalent to the letter's numerical value. For example the EOT character with a value of 4 is represented as ^D because D is the 4th letter in the alphabet. The NUL character with a value of 0 is represented as ^@ (@ is the ASCII character before A). The DEL character with the value 127 is usually represented as ^?, because the ASCII '?' is before '@' and -1 is the same as 127 if masked to 7 bits. An alternative formulation of the translation is that the printed character is found by inverting the 7th bit of the ASCII code
The full list of ASCII control characters along with caret notation can be found here
Regarding vim and other text editors: You'll typically only see ^M if you open a Windows-formatted (CRLF) text file in an editor that expects Linux line endings (LF). The 0x0A is rendered as a line break, the 0x0D right before it gets printed as ^M. Most of the time, editor default settings include 'automatically recognize line endings'.