Here are some examples of how it might be used:
* "He harkened after fame and fortune, but found only disappointment."
* "She harkened after knowledge, spending hours in the library."
It's important to note that "hearken after" is more often used in the context of seeking something abstract, like fame, knowledge, or ideals, rather than pursuing a physical object.
Here are some synonyms that you could use instead of "hearken after" in modern English:
* Pursue
* Chase
* Strive for
* Seek
* Long for
* Aspire to
For example, instead of saying "He harkened after fame," you could say "He pursued fame."