In the desktop I am able to see "Notes & Attachments" related list on the Opportunity. But When looking the same opportunity in Mobile (Salesforce1) not able to see Notes & Attachment.
How to enable that in mobile Can anyone please help me with this ?
Salesforce1 is indeed built on Aura, as confirmed in Josh Kaplan's (Salesforce Aura Product Manager), Dreamforce 2013 session, Introducing Aura: Rapid Mobile Development with Reusable Components. It is also using the Salesforce Mobile SDK as well. This great collection of Dreamforce 2013 sessions featuring Salesforce1 also references the Aura session. Salesforce drinking its own champagne!
In that presentation btw, Josh and his team give some great insight into how production grade Aura really is, the journey they have taken with it since Salesforce Touch (which also used an early build) and a sneak peak at where it is going as native platform feature! I personally cannot wait, one to watch!
The source code is shared in GitHub, so you can even try it out and contribute!
Well finally I decided to install the Approval Central for Salesforce1 app from AppExchange. This app is from Salesforce Labs. Probably they want to give this as an add-on instead of a basic feature.
Once this Tab was added, it comes up fine on the mobile device. 
Best Answer
Notes are now available in salesforce1 but not attachments. See the idea delivered in winter 16: https://success.salesforce.com/ideaview?id=08730000000Bpd6AAC