Is it possible to reinstall S Notes after flashing Lineage OS 14.1 on Samsung Galaxy Note 8?
S Note is tightly integrated with Samsung's framework and thus can't be ported to non-stock-based ROMs.

In the meantime, try Squid as an alternative. Lots of available pre-defined notes, export to PDF, and best of all it makes use of the spare button on the pen that LineageOS doesn't use.