Yes. For this, you'll need to sweep the private key into your wallet (note: you'll have to pay the TX fee if you want to do this, you can optionally just import it if you don't want to pay the fee, but that's not recommended).
Open Electrum, and if you are going to create a new wallet, make sure to remember the seed!
Then sweep the private key: Wallet -> Private keys -> Sweep...
REMEMBER TO ENCRYPT THE WALLET WITH A SECURE PASSWORD AND DO NOT COPY THE SEED TO YOUR CLIPBOARD. DO NOT STORE THE SEED ON ELECTRONIC DEVICES.
DO NOT LOSE YOUR SEED. WRITE IT ON TWO PIECES OF PAPER AND MAKE SURE THAT NOBODY ELSE CAN READ THEM - IT'S RECOMMENDED TO STORE THEM IN A SAFE

Again, remember to make a backup of your (encrypted) wallet and the seed.
Treat the seed as your private key and never disclose it.

If my posts have helped you, please consider a small tip ↓

First - DO NOT USE  blockchain.info, they are untrustworthy and can steal your coins.
Webwallets are incredibly insecure. I recommend using Bitcoin Core or Electrum. Don't forget to encrypt your wallet with a strong password and to make backups!

Also, never, and I mean it - NEVER copy-paste your private keys! Write them down on a piece on paper instead.
You should also make a Linux (such as Ubuntu or Debian) live USB (even if you already have an installation - it may be infected!) and boot from it to do the following.

Your casascius coin should contain a so-called mini private key under the shiny holographic label, it's going to look like S6c56bnXQiBjk9mqSYE7ykVQ7NzrRy.
This is a mini private key, which can be converted to a normal WIF one in multiple ways.


One simple way is to use bitaddress.org (Wallet Details tab) and entering your mini private key there.
WARNING: Do not use it online. I recommend downloading the repo offline (https://github.com/pointbiz/bitaddress.org/archive/v3.3.0.zip) (download link for the zip linked at the bottom of bitaddress.org).

After downloading the zip, unplug your Ethernet cable, and/or disconnect from the WiFi (make sure to disable it!).
Now, extract it in your home directory (you should be using Linux to follow the tutorial, didn't I tell you?), open it in a file explorer and double-click on the file named index.html)

Congratulations - you're running bitaddress.org offline.

Now open the Wallet Details tab and enter your mini private key there. Your address along with the WIF private key will be displayed, carefully write it down and double check.
You can then sweep this private key in your wallet of choice.

Tip: you don't need to do that if you are using Electrum, as it already supports mini private keys.

Indeed we do Thanks for confirming that.

I am not willing to bid 6 BTC for an ungraded coin in current conditions, but if you are prepared to lower the starting price, I am certainly willing to participate in this auction

Please let us know if you will accept escrow. As you have very little history on this forum, no one is going to trust you blindly, people have been scammed too many times.
Further, if this was graded, 6 BTC start might be okay. If you want action though, I suggest starting this @ face value of 5 BTC. Your choice Good luck!!

I hope he does really have a collectible coin, or he's just really confused and he saw the prices of bitcoins and suddenly he wanted to convert. I hope he doesn't have just a simple coin that isn't loaded or anything. Since the prices are going crazy, so are the people using them.

Just a suggestion:

Your pricing for the 5 btc nickel is a little steep for an ungraded one. It's a nice coin though.