You can use symbols in a Sequence label. See the Use Guide Article Edit the Sequence Name Label Displayed in Map View to learn how to edit the sequence label.
Whilst editing the Sequence label, click on the Symbol buttons to add specific symbols to your sequence name.
Description and Comments
You can use symbols in the Description panel sections "Description" and "Comments". See the User Guide Lesson Add Descriptive Information to a Sequence File for more information.