During I/O conference Google said that they will launch the option of mirroring Android devices to Chromecast, and last week by keeping their words Google pushed out mirroring functionality to Chromecast. But this cast screen option is only available for selected devices as of now.
And now a third party app, MirrorEnabler is here which will let you to mirror your Android device to Chromecast.
As of now the update is only compatible for most devices from Samsung, Sony and HTC including: Samsung Galaxy Note 8, Samsung Galaxy Note Pro 12.2, Sony Xperia Z2 and the Verizon HTC One M8. The app was also tried out on Samsung Galaxy Note 2 and Galaxy S3, but it received mixed results.
It will show some bugs as its in beta version but it is working perfectly well with the above mentioned devices.