No on so many levels. You want to record sound with dedicated sound recording equipment.
What does that offer aside being a pain in the bum?
You decide you are recording something and you get your iPhone recorder set up nicely and then decide you need to phone someone, or look up some information, or send a text, or receive a text.
It it was £10 it would still be a waste of money, as it is it is well on its way to the cost of a DR-05 which would be by far the better solution.
It is about as silly as the strap on telephoto lens, and about as useful.
In my humble opinion. 