Apple over the years has been migrating to more assemblies than discreet parts. The display in this series is very difficult to open and so far Apple has not offered the discreet parts.
Your best bet here is to replace the complete assembly. Here's the part you'll need: [product|IF301-002|MacBook 12" Retina (Early 2015) Display Assembly P/N 661-02241] and here's the IFIXIT guide you'll need to follow: [guide|44274|Retina MacBook 2015 Display Assembly Replacement]