You can sync your MetaMask extension wallet with mobile by using the MetaMask Mobile Sync feature.
1. Install MetaMask mobile at MetaMask.io.
2. Open the MetaMask mobile app and select ‘Sync or Import’ > ‘Scan QR code’.
3. Log into your MetaMask extension
4. Click Settings > Advanced > Sync with Mobile. You’ll see a QR code.
5. Scan this QR code with your MetaMask mobile app (see step #2).