How to audit all DML operations on a SQL Server 2008 R2 database
If you just want to know number of index updates (regardless of how many rows affected, how wide the indexes are, etc.) and as long as you can be sure the service doesn't get restarted or indexes dropped/re-created in that timeframe, then you can look at sys.dm_db_index_usage_stats now and after a couple of days.

As suggested by Kin, have a look at Nacho's FAQ. Basically:


The DMV can reset if:


the server is restarted
an index is dropped and re-created

The DMV can be empty if you start with -x, -m, or trace flag 2330
If you have a filtered index, updates will increment the usage stats even if the update did not affect the rows in the index
If any column in the clustering key is modified, all non-clustered indexes also increment their usage stats
Errors occurring after a DML attempt is made will still increment counters
Index usage tells you number of operations - it does not have any way to report to you number of rows or pages touched (an update to every row in a very wide table looks the same as an update to a single row in a very skinny table) - if you want more details on actual volume touched, see sys.dm_db_index_operational_stats.


And also Tim Ford's series on snapshotting the DMV:


Retaining historical index usage statistics for SQL Server : Part 1 | Part 2 | Part 3