The MP for Lichfield, whose hair has often been subjected to speculation, was asking Theresa May a question about business in the West Midlands when Mr Merriman was caught gesturing towards his hair.
The MP for Bexhill and Battle could be seen in the background appearing to mouth the words: “It’s a wig.”
Mr Fabricant was made aware of the footage on Twitter, and responded to the clip on social media.
“It’s Huw Merriman MP. I realise no-one knows him,” he wrote.
“A newish member, a little short sighted, and who doesn’t yet realise that PMQs are televised, bless.
“I know people are annoyed about his antics, they have been calling my office, but he’ll eventually learn how to behave. Sweet.”
Mr Merriman has been a member of parliament since the 2015 general election, the Press Association has approached him for comment.