There’s a great history of poets writing poems that declare they’re not poems. From Joyce Carol Oates’ THIS IS NOT A POEM published by the New Yorker:
in which the poet discovers
delicate white-parched bones
of a small creature
on a Great Lake shore
or the desiccated remains
of cruder roadkill
beside the rushing highway.
To Brian Bilston:
Today write a poem that declares itself not a poem but becomes one in the process.