How to read Delve Custom Aditional Field from Graph API

Hi All,

Could you please explain how to   read Delve Custom Aditional Field for all users  from Graph API 

we are able to read AAD field of all users  from graph API via https://graph.microsoft.com/v1.0/users?$top=1 

we need to sync our custom .net application from via AAD and Delve user aditional custom field.