Sending Messages between 2 c++ process

In order to make two objects, Player 1 and Player 2, of a class Player sending and receiving messages, I implemented a blocking queue to synchronize the messages. This is the code I used:

 class Message 
    {
    public:
        Player* sender;
        std::string text;

     };

    template <typename T>
    class BlockingQueue
    {
    public:
        void push(const T& val)
        {//code}
    
        T pop()
        {//code}
    
    };

    class Player
    {
        BlockingQueue<Message > queue;
    
    public:
        
        void sendMessage(const string& message, Player *dest)
        {
 Message msg;
         msg.sender= this; // sender 
         msg.text = message;
         dest->queue_.push(message);
        };
    
        void run()
        { 
          while (true)
          {
            Message msg= queue_.pop();
            // do something with the message
            sendMessage("somehing",msg.sender);
          }
        }
       };

int main()
{
    Player player1("player1");
    Player player2("player2");
    thread thread1([&](Player* player) { player->run(); }, &player1);
    thread thread2([&](Player* player) { player->run(); }, &player2);
    player2.sendMessage("Hi",&player1); // send message to player2 (from  player 1)
    thread1.join();
    thread2.join();

    return 0;
}

what I did here ! is send messages between the two objects of class Player through one single process.

How Can I have every player in a separate C++ process?