Can I insert Unicode symbols on iPhone?

On my iPhone, I like to insert checkmarks in calendar items that I complete. I've found two ways to do it so far:

1) Insert a checkmark emoji

2) Create a keyboard shortcut named "ck" with the phrase being a cut/paste of a Unicode checkmark from a web page.

Obviously, the iPhone supports the Unicode checkmark character, but I can't find any way to directly access special Unicode symbols. Is it possible to call up a screen of Unicode symbols for text insertion?