(Form TextBox) Multiple Fonts

I need to use two types of fonts to not only display a string of characters in a textbox but also past to a cell as viewed in the textbox.

An example string:

[#|:.010(M)|A|N(M)|B(M)]

The above string in Arial font would look like this:

[TP|Ø.010(M)|A|N(M)|B(M)]

I am simulating a GD&T instruction (Geometric Deimensioning and Tolerancing).

My dilema stems from the first character "[" and the last character "]".
I use both of these characters to open an instruction and close the instruction (as if all characters are surrounded by a rectangle).

What I cant figure out is how to isolate the first "[" and the last "]" (They will always be the first and last characters of an unknown string length). The first "[" would be an "Arial font" and the last would be an "Arial font" everything in between is another font (in this case Verisurf).
See attached example jpg file.
"verisurf1.jpg"

Verisurf uses both "[" and "]" as alternate characters. I only need to capture the first and last character if: 1. The first is a "[" and or the last is a "]". They will never be vice~versa.