How to select data whose column_name data has digits only in PostgreSQL?

How to select data whose column_name data has digits only in PostgreSQL?

How to select row data whose column_name has digits only in PostreSQL?
Like when table has:
ID | Column_name
1 | 000012
2 | ABC001
The expected result on select should only be the ID 1 wherein the
Column_name has only digits.
I have tried this code but does not work:
select * from table Where not Column_name like '%[^0-9]%'
Can anybody give me advice? Thanks