Hi Mirtemir
Question - do both phone numbers display on the user profile in columns (fields) or are they in a grid? the reasion I ask is because you are using a "First" expression which is normally used to to consider on the first record retrieved.
I am going to assume you want to show both mobile numbers in one field in a single input on a canvas app.
Firstly you should add an Office365User Connection.
Next create a add a label to get the UserID, for this you can user the following expression

Next add in input and use the following expression

Office365Users.UserProfile(Label7.Text).mobilePhone & " - " & First(Office365Users.UserProfile(Label7.Text).BusinessPhones).Value
I know this is not exactly what you are trying to do, however, once you are able to retrieve the data you can then write an If expression to manage how the data is displayed.
I hope this helps.