To get column level CDC firstly we must create CDC for the table in previous tutorials i have already explained How to create the CDC for tables and Databases , how to check whether cdc is enabled or diabled  and How to disable CDC for tables and databases, This function will show how many column level ordinals based on  the Change Table(_CT)

sys.fn_cdc_get_column_ordinal ('capture_instance','column_name')

capture_instance is, in which instance the object had been created, Like dbo,sys,etc and the table name as Shown below example.

select sys.fn_cdc_get_column_ordinal('dbo_yourTableName','YourColumnName')

By executing the above function with valid parameters you will get the ordinal for the column mentioned.