Hi @zina mevzos , I don't think Graph API supports Lockbox currently as it's still in preview. There are 2 Github samples that may help you connect it with Azure Management.
- https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/security/fundamentals/customer-lockbox-overview.md
- https://github.com/Azure/azure-rest-api-specs/blob/main/specification/customerlockbox/resource-manager/Microsoft.CustomerLockbox/preview/2018-02-28-preview/customerlockbox.json
Please let me know if you have any questions or if I misunderstood yours.
If this answer helped you please mark it as "Verified" so other users can reference it.
Thank you,
James