As I understand, you need that your ToC had portions of text with a different font. I’m afraid, it’s impossible. ToC uses its paragraph style to assign font settings, so it will change your font (you may, of course, torn off the protection against manual changes in ToC settings, and then change it manually, but this will not survive refreshing the ToC).
If possible, try to use the font that has the required symbols for both your headings, and your ToC. To define the ToC font, use Contents Heading
and Contents N
paragraph styles (the former is under Heading
styles group, the latter are under Index
styles group in Styles and Formatting
sidebar).