You can add data into a Custom Field on your Mobile phone. 

1. Log into your CRM account via your mobile screen:

2.Click into contacts and then open contact record.  

3. At the bottom of the screen will give you option to select Custom Field.  Click this and it will list the custom field in text format.  

4. Enter in the information into the Custom Field. 

5. Click on 'Update' to Save.