In the animated series "Miraculous: Tales of Ladybug & Cat Noir," Hawk Moth (Gabriel Agreste) does not transform into Lady Noir after obtaining Cat Noir's Miraculous. Instead, Hawk Moth seeks to capture Ladybug's Miraculous to use its power along with Cat Noir's Miraculous for his own purposes.
In the series, transformation into a different character or identity typically requires the use of a specific Miraculous and does not follow the line where a villain transforms into a hero character like Lady Noir. If you're asking about a specific episode or fan theory, please provide more details!