If you are talking about table structure then use,
for table modifiction
select Name,create_date,modify_date from sys.objects where type='u'
you can fetch column update's date if column is primary key/foreign key like this
select Name,create_date,modify_date from sys.objects where type='p' or type='F'
for all columns modification date, you have to put trigger on table modification. and save entries inside a new table.
Note: when ever you will rename column table-modification trigger will not be fired. so, that case you will not able to save 'renamed' column's changes.
Happy Coding!
:)