How to express it?
I heard the phrase on/from/through a podcast.
I found the phrase on/from a podcast.
I learned the phrase from a podcast.
Which preposition is correct? or How would you say it?
Thank you.

Question

How to express it?
I heard the phrase on/from/through a podcast.
I found the phrase on/from a podcast.
I learned the phrase from a podcast.
Which preposition is correct? or How would you say it? 
Thank you.

Answer

I would use "I learned the phrase from a podcast."

Answer

I heard the phrase on a podcast.
I learned the phrase from a podcast.

The above two are correct - "found" is a slightly strange verb to use in that context.