Tracking field value change across components

Hi ,

I want to maintain a custom field with timestamp value in crmd_customer_h based on changes done on opportunity header field like probability field present on opportunity header (BT111H_OPPT->Details->BTOPPORTH->STRUCT.PROBABILITY).

This custom field has been created through EEWB .

Now this field is present in a different z component/view and this view is added in opportunity header overview in a different assignment block .

Now requirement is to update this field in db table (and ui ) when probability is changed on opportunity header. I am trying to code for this in get method of field created but i am not able to identify here whether probability got changed and initial values of probability present in opportunity header .

Basically i have to track field value change in COMP1/VIew1 and then update field present in COMP2 /View2 .

COMP2 has been defined in component usage of COMP1

Can anyone guide me how to proceed for this requirement ?

regards

Piyush