The Haftarah of Pinchas is read very rarely. Usually, it is already the first of the Three Weeks, which have special Haftarot of their own. It is from Melachim I, continuing the story told in the Haftarah of Ki Tisa, of Eliyahu at Har HaCarmel.
Linear Annotated Translation of the Haftarah of Pinchas
As to what Pinchas and Eliyahu have in common, to the extent that the Midrash has a tradition that they are the same person: Pinchas – Outrage