Can you post a link to where you heard this? To my knowledge "sought" is never pronounced this way in modern English.
It's very possible there is a dialect somewhere where this is the case - "gh" used to make the sound of a German "ch" in English, and there have been dialects in English where the German "ch" sound became a hard "k" sound it became silent in other dialects (the latter of which became the standard pronunciation of English). I know there are parts of Lowland Scotland where "gh" is still pronounced with the original German "ch" sound, so it's very possible there's somewhere where the "gh" in "sought" is pronounced with a hard "k".
Having said that, I would be very, very surprised if such a pronunciation turned up somewhere in the US. I would expect such a dialect that preserves this pronunciation would be somewhere in rural Britain, but I'm happy to be proven wrong.