Create a codeblock tool

V, 4 bytes

Î4É 

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(Note the trailing space)

V is encoded in Latin1, where this is encoded like so:

00000000: ce34 c920                                .4. 

Explanation

Î            " On every line
 4É<space>   " Prepend 4 spaces

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Here's a solution that is also 4 bytes in UTF-8!

VG4>

VG          " Select everything
   >        " Indent
  4         " 4 times (with spaces)

Crayon, 7 bytes

`¤q;3xq

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Explanation

Crayon is a stack-based language designed for creating ASCII-art. It's still in the early stages of development, but it knows just enough to finish this challenge with a rather low byte count:

         Implicit: input string is on the stack
`¤       Push a non-breaking space to the stack.
  q;     Draw this at the cursor (0,0 by default) and pop it.
    3x   Move three more spaces to the right.
      q  Draw the input string here (at 4,0).
         Implicit: output the canvas, trimmed to a rectangle

Drawing the non-breaking space is necessary because Crayon automatically trims the output to a rectangle, so without the NBSP it would just print the original input.

Retina, 8 bytes

%`^

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There are four spaces on the second line. Alternative solutions use either m`^ or %1` or 1%` on the first line. All of these match the position at the beginning of each line and replace it with four spaces.