Use Master Pages for items that need to match exactly
You have to import the symbol as AI file. You can anchor it to the text, the exact position can be done with an object style and can so globally be changed if needed.
I would not put it on the master as it is part of the content. On the master must never be anything content alike, only background, page numbers, running headers, never a part of content. That is why because upon export as EPUB master page items are ignored (except with EPUB 3 fixed) and if you need to export as PDF/UA (unlimited access standard) it will be ignored for help devices for people with impaired seeing capabilities.
I'm interpreting this that the text might not be positioned in the same spot from page to page, but you want your symbol in the same place relative to the text. I think you could do this with a bulleted list style, and use your symbol for the bullet. If you need to make the symbol into a font to accomplish this, you can use the trial of IndyFont to make a single character font that should work: Adobe Community: [Ann] IndyFont Demo: make your own (1 character) font