First of all, it is micro , as the name suggests. It is a very short text, sometimes even a single word, which however perfectly encapsulates the message it has to convey.
#1 It's simple
If it is to dispel fears, avoid frustrations and push for conversion, it must be simple for the user to understand, it must not make him think too much. Use clear words, commonly used, maybe even colloquial (always based on why choose our service personality and ToV), get straight to the point and give a direct indication.
Microcopy CTA from Paypal site
From the Paypal website , a simple and direct call to action: it indicates a reason for carrying out that action (“make your life easier”) and an immediate action to take (“buy online now).
#2 It's original
Here we return to the introduction. “Send” in a form meets the requirements: it is short and simple, more direct than that! But it is not original, in fact it is quite impersonal and standard. A well-studied microcopy is able to amaze, to make people smile, to excite. Everyone knows how to choose the easiest way, but to be successful you have to know how to dare . Here is an excellent example.